(1) Field of the Invention
The present invention relates to novel pigment dispersants and pigment preparations having improved coloristic and rheological properties and to their preparation and use for pigmenting high molecular mass materials.
Pigment preparations are combinations of pigments and pigment dispersants that are structurally analogous to pigments and are substituted by groups having a specific activity. The dispersants are added to the pigments in order to facilitate their dispersion in the application media, especially in varnishes, and to improve the rheological and coloristic properties of the pigments. The viscosity of the highly pigmented paint concentrate (millbase) is lowered and the flocculation of the pigment particles reduced. This makes it possible, for example, to enhance the transparency and gloss. Such enhancement is particularly desirable in the case of metallic pigments.
There are a large number of proposals for improving the rheological and coloristic properties of organic pigments by adding pigment dispersants, but they do not always lead to the result hoped for.
For instance, EP-A-0 321 919 describes the production of pigment preparations by mixing the base pigments with pigment derivatives containing methyleneimidazolyl groups. EP-A-0 877 058 describes the preparation of carboxamido-containing pigment dispersants, and pigment preparations comprising these pigment dispersants.
DE-A-3 106 906 describes the preparation of sulfonamido-containing pigment dispersants. Pigment dispersants based on diketopyrrolopyrrole compounds, however, are not mentioned.
JP H3-26767 describes sulfonamido-containing pigment dispersants based on diketopyrrolopyrrole compounds. The pigment preparations produced with them, however, do not meet every requirement imposed on pigment preparations in respect of the performance properties. For instance, their solvent fastness and fastness to overcoating is inadequate, so greatly restricting their universal application.